This invention relates to a process of forming a gasket. More particularly, the invention relates to a process of forming a gasket with a minimal production of waste material.
Gaskets are widely used for providing seals between pairs of confronting surfaces, such as between engine blocks and heads in internal combustion engines, and the like. Gaskets used in such applications must provide an effective seal between the relatively large number of interconnecting cavities carrying fluids of different types and under different pressures so that the fluids do not intermingle or leak externally.
Currently, gaskets are prepared from sheets which are typically made by the Fourdrinier paper process. In that process, sheets are made by continuously depositing latex treated fibers (stock) from a very low consistency aqueous suspension onto one end of a Fourdrinier wire. A Fourdrinier wire is a relatively finely woven endless screen belt that travels around and between two large rolls, a solid breast roll at a headbox from which the stock is discharged onto the belt, and perforated couch rolls having vacuum chambers inside. The partially dewatered stock then passes over suction boxes that drain away at least 95 percent of the water, leaving a wet paper web on the upper surface of the belt. The web is removed continuously from the wire at, or closely following, the end of the suction zone in the couch roll. The wet paper web is subsequently pressed to remove any remaining excess water and is then dried prior to being transferred to a reel.
U.S. Pat. Nos. 4,448,640, 3,654,076 and 3,064,727 disclose rotary pulp-molding machines in which pulp is picked up from a slurry in molding dies, and is then transferred, frequently by an intermediate device, to a conveyor belt. The intermediate device may remove some of the water. The resulting object shaped by the molding dies, such as a pulp tray or the like, is then carried by the conveyor belt through a dryer to remove excess water.
Problems have been encountered in current processes for forming gaskets, as by using Fourdriner wire and/or pulp molding machines both of which are used to produce solid sheets which require subsequent die cutting, in that a significant amount of waste material is produced. Further, separate and additional treatment of the gaskets formed thereby is required to add thickness and strength to desired areas of the gaskets. Thus, a gasket-forming process that produces a minimal amount of waste material, as contrasted to conventional gasket forming processes in which up to 60% of the sheet is cut away and wasted, and one which produces gaskets exhibiting differential thicknesses and increased strength in specified areas is to be desired.